Effluents Wastewater industries pollute fresh water. The same applies to the settlements, which also pollute the water. As a result of this contamination completely change the physical properties of water (the temperature decreases transparency, there are color, taste, smell). There are floating substances found on the surface of water in the bottom sediment settles. The composition of water is completely changed: increased content of organic and inorganic substances, there are toxic substances, reduced oxygen content, changing the active reaction "environment and others. Changes occur also in qualitative and quantitative bacterial composition, occurring bacteria Such water is unfit for drinking. It not even suitable for technical purposes, of course, fishery purposes.

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Domestic waste water The best known source of water pollution, which has traditionally paid the main attention is domestic (or municipal) waste water. Water consumption cities usually estimated based on the average daily water consumption per capita in the U.S. at about 750 l and that includes drinking water, cooking and personal hygiene for household plumbing devices as well as for watering lawns and lawns, firefighting, street cleaning and other urban needs. Almost all of the used water goes into the sewer. Since the day the waste water enters the huge volume of feces, the main task of urban services for the processing of sewage treatment plants in reservoirs is removing pathogens. Repeated use of inadequately treated human waste water they contain bacteria and viruses can cause intestinal diseases (typhoid, cholera and dysentery), and hepatitis B and polio.

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Radioactive substances Exposure to toxic metals. These toxic metals like mercury, arsenic, cadmium and lead, too, have a cumulative effect. The result of the accumulation of small doses can be the same as when receiving a single large dose. Mercury contained in industrial effluents, is deposited in the sediments of silt in rivers and lakes. What living in the provinces anaerobic bacteria transform it into toxic forms (eg, methylmercury), which can lead to serious injury of the nervous system and brain of animals and humans, and cause genetic mutations. Methylmercury - volatile substances released from the sediment, and then with water ingested fish and accumulates in the tissues. Despite the fact that the fish do not die, people who ate contaminated fish this can poison and even die. Another well-known poison, which come into dissolved in streams is arsenic. It was discovered in a small but quite measurable amounts of detergents containing phosphates and soluble enzymes, and colors for coloring cosmetic napkins and toilet paper. Since industrial effluents into the waters fall as lead (used in the manufacture of metal products, batteries, paints, glass, gasoline and insecticides) and cadmium (which is used mainly in the manufacture of batteries).

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Thermal pollution The temperature of water used in thermal power plants for cooling steam rises by 3-10 ° C, and sometimes up to 20 ° C. The density and viscosity of the heated water different from those of colder water makes the pool, so they shuffled slowly. Warm water cooled or around the place of discharge, or mixed flow, current down the tech? Niya River. Powerful power noticeably heated water in rivers and bays, where they are located. In the summer, when demand for electricity for air conditioning is very large and its production increases, these waters often overheat. The concept of "thermal pollution" refers to such cases as excess heat reduces the solubility of oxygen in water, accelerates the rate of chemical reactions and thus affects the lives of animals and plants in the intake basins. There are striking examples of how the resulting increase in water temperature the fish died, there were obstacles to migration, rapidly multiplied algae and other lower weeds occurred late seasonal changes in the aquatic environment. However, in some cases, increased catches of fish continued growing season and were seen more favorable outcomes. Therefore, we emphasize that a more correct use of the term "thermal pollution" should have much more information about the impact of additional heat in the aquatic environment in each location. Accumulation of toxic organic substances. Stability and toxicity of pesticides ensure success in the fight against insects (including mosquitoes), various weeds and other pests that destroy crops. However, it was shown that pesticides are also environmentally harmful substances, so that accumulate in various organisms and circulating within the food or trophic, chains. Unique chemical structure of pesticides not amenable to conventional processes of chemical and biological decomposition. So when plants and other living organisms, treated with pesticides, consumed animals, toxic substances accumulate and reach high concentrations in their body. As the larger animals eat smaller ones, these substances are at a higher level trophic chain. It occurs both on land and in the waters.

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Diseases which causes consumption of contaminated water Cholera, dysentery, hastroentryt, letospiroz, cancer, tularemia, malaria, hepatitis, intoxication, poisoning, and many other diseases that can lead to death.

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Water consumption

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Today embarrassment is not only fewer, but also reduce the quality of groundwater, and in recent years scientists have drawn attention to the high concentration of solid particles that are found in the groundwater. In homes, which receives water underground reservoirs, the water is much harder. Removing too much water from wells on farms thereby lowering horizons water and sea water can sometimes penetrate deep into the land and, therefore, the zone of saturation. The water in the wells in this area becomes salty and unfit for consumption.